Multiple stage air compressor



3, 1949. R. E. MITTON 2,479,856

MULTIPLE STAGE AIR COMPRESSOR Filed Sept. 17, 1945 '6 Sheets-Sheet 1,Aug. 23, 1949. R. E. MITTON 2,479,856

I MULTIPLE STAGE AIR COMPRESSOR Filed Sept. 17,- 1945 I e Sheets-Sheet 2Wmmzzw/ R. E. MITTON MULTIPLE STAGE AIR COMPRESSOR Aug. 23, 1949.

6 Sheets-Sheet 3 Filed Sept. 17, 1945 i gx R- E. MITTON MULTIPLE STAGEAIR COMPRESSOR Aug. 23, 1949.

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Aug. 23, 1949.

R. E. MITTQN MULTIPLE STAGE AIR COMPRESSOR 6 Sheets-Sheet 6 Filed Sept.17. 1945 VV /l/flf/MllM/ N/ 7 o 9 f n vanfom I W 5/. MW

dilating J Patented Aug. 23, 1949 MULTIPLE STAGE AIR COMPRESSOR RobertE. Mitton, Lemongrove, Cali! assignor of fifteen per cent to D. W.Sneath, El Cajon, one per cent to Edwin T. Padfleld, La Mesa, one percent to Alvin G. Crawford, National City, one per cent to. George H.Roberts, National City, one per cent to Noah H. Highsmith, San Diego,and two per cent to Lynold L. Claydon,

San Diego, Calif.

Application September 17, 1945, Serial No. 618,714

2 Claims.

My invention comprises a multiple stage air compressor and morespecifically a multiple stage air compressor which can be operated fromany source of fluid power either by steam, compressed air, hydraulicallyor by power derived from an induced vacuum.

In my compressor there is no mechanical linkage or connecting rods. Allthe parts are actuated by the fluid pressure moving through a series ofports and slots. The only operating members are reciprocating pistonsand valves which do not have connecting rods or cams.

It is therefore the object of my invention to provide a multiple stageair compressor in which the pistons and valves are directly motivated bythe fluid pressure transmitted through ports in the engine housing.

Another object of my invention is to provide means to actuate thepistons and valves of my compressor through open connections withoutmechanical linkage or connection between the pistons and valves in therespective stages or in the compression chambers.

Another object of my invention is to provide a compressor which can beeffectively operated when installed at any angle and which may beactuated by steam, air pressure, hydraulic pressure, gas or otherexpansive fluid or by an induced vacuum.

Another object of my invention is to provide a compressor which can bereversed in action and used to create a vacuum for laboratory or otherpurposes.

Another object of my invention is to provide a compressor which can beused on trucks, automobiles and the like to compress the air used in airbrakes and which can be actuated by the same source of power as theconventional windshield wiper, i. e., from the vacuum formed in theengine intake manifold.

In the following description the preferred embodiments of my inventionare set forth.

In the drawings:

Figure 1 is a top plan View of my invention;

Figure 2 is a side elevation;

Figure 3 is a cross-section taken on the line 3-3 of Figure 1;

Figure 4 is an end elevation;

Figure 5 is a cross-section taken on the line 55 of Figures 2 and 3;

Figure 6 is a cross-section taken on the line 66 of Figures 2 and 3;

Figure 8 is a cross-section taken on the line in accordance with myinvention comprises a se- Figure 7 is a cross-section taken on the lineries of castings bolted together. A central casting forms a housing Ifor the engine operating mechanism. Castings 2 and 3 bolted on the endsof the housing I comprise housings for the multiple stage compressor andcarry slots and bores for the actuation of the engine installed in thehousing I. At the ends of the castings 2 and 3 are the cylinder heads 4and la, respectively.

It should be understood that my compressor can be either a single stage.double, triple, or multiple stage without departing from the spirit ofmy invention, and in the preferred form shown in the drawings, to behereinafter described, is shown a triple stage com ressor.

In the castings 2 and 3 are bored the low pressure cylinders I and 8,intermediate cylinders I and 0 and the high pressure cylinders 9 and M.In the engine housing I is bored the cylinder H which carries thedriving piston ll for the low stage compressor, cylinder I! for thepiston oi the intermediate compressor and the cylinder l3 for the pistonof the high stage compressor. These pistons are numbered, respectivelyII, I! and ii. In the cylinders 5, 6, l, 8, 9 and III are positioned thecompressor pistons l1, l8, i9, 20, 2| and 22 which are connectedtogether by the piston rods 23, 24 and 25 which connect the pistons ofthe compressor of the same stage together with the driving piston ofthat stage. It should be noted that the compressor situated in thecasting 2 and the one in casting 3 are identical except that they are inopposite phase to each other. Therefore, I shall describe only theoperation of the compressor in the casting 3 as the other compressor andits action are identical.

In the cylinder heads 4 and 4a for each stage of the compressor arepositioned inlet and outlet valves. The inlet valves comprise a rubbervalve 28 carried by the valve'stem 21 and actuated by 8 pring 28 thatcauses the same to sit on a valve seat 29. The outlet valves comprise arubber valve 3| mounted on a valve stem 32 and held closed by a spring33. A valve 28 opens the cylinder 8 to the atmosphere through the port38 and acts as the inlet to the com ressor. When the piston I8 is movedto the left in Figure 8, the suction applied to a valve 28 causes thesame to open against the pressure exerted by the s ring 28 and to drawair into the cylinder 8. When the piston I8 is moved to the right, andstarts to compress the air in the cylinder 8, it forces a valve 28 toseat, sealing the port 38. When the pressure in the cylinder 8 becomessufficient a valve 3| is moved from its seat 34 opening the port 35.allowing the air in the cylinder 8 to be forced through the port 38 andthe bore 38 into the cylinder 8, past a valve 28. Similarly when thestroke is reversed. the piston 28 will force the air previously forcedinto the cylinder 8 by the piston l8 out through a valve 3|, through thebore 31 into the cylinder l8 past a valve 28. Again, when the piston 22is in its compression stroke, it forces the air out through a valve 3|through the outlet port 38 into whatever type of supply or compressionchamber is connected-to the compressor. When the pistons l8 and 22 arein their compression stroke, the piston 28 is in its intake stroke.

To o erate this triple stage compressor I have provided the enginepositioned in the housing I whose actuating members are the pistons l4,l8 and I8. To actuate these pistons and drive the compressor I provideangenaine valve 48 positioned in the cylinder 4|. The engine valve 48communicates with the port 42 which is the intake for fluid pressure,and with the port 43 which is the exhaust. The engine valve 48 has atits ends pistons 89 upon which it slides back and forth in the cylinder4|. At the ends Just inside of the pistons 88 are annular grooves 44 and45. On one side of the valve 48 is a flatted surface 48 which opens intothe annular grooves 44 and 45 and communicates with the inlet port 42.On the other side of the valve 48 is a milled slot 41 which communicateswith the exhaust port 43. When the engine valve 48 is moved to the rightin Figure 3 or 11, the fluid pressure can then flow throu h the port 42out through the annular groove 44 into the bore 41a which communicateswith a slot 48 milled in the face of the casting 2. This slotcommunicates with the end of the cylinder 13 and allows the fluidpressure-to flow into the cylinder IS on the left side of the piston 16.This pressure will thus force the piston it to the right. At the sametime a milled slot 49 in the face of the casting 3 allows the exhaustfluid in the cylinder l3 to be forced out through the slot 49 and theport 58 past the milled slot 41 and through the exhaust 48. By movingthe engine valve to the left, the exhaust and intake are reversed, andthe piston l8 would be forced to the left. To drive the other two stagesof the compressor emerging from the cylinder I3 is a port which opensinto the slot 52 communicating with the bores 58, 54. 88 and 58 and theports 58, 51 and 58. The port 88 enters into the cylinder l l at theleft end, and the port 58 enters into the cylinder 8 at the left end,and the port 51 enters into the cylinder l2 at the right. When theengine valve 48 is at the right end it admits pressure on the left sideof the pistons l4, l8 and I8 and the right side of the piston l5. As oneof the chief purposes of my multiple stage compressor is to act as anair compressor for air '4 brakes on trucks and other motor vehicles. andI plan to drive the same from the vacuum created by the intake manifoldof the engine. it is apparent that the driving energy of my compressoris rather small and to secure sufllcient pressure to actuate the lowstage compressor I have found it desirable to use the pistons I1 and I8as driving pistons as well as the piston 14. This is accomplished by thecross porting, such as the port 88 which opens into the cylinder at theleft of the piston I 8. The reverse stroke of the pistons l4 and I8 isactuated by the fluid emerging from the cylinder I3 at its right endthrough the bores and ports identical with, but

.of an opposite pattern to, those leading from the left end and openinginto the cylinders 8, H and i 2 on the opposite side of the pistons l4,l8, l1 and I 8. For purposes of clarity I have numbered these ports,bores and slots 8la, 82a, 83a, etc., to correspond with the firstdescribed ports, etc. Byreversing the engine valve 48, the piston isthus connected through this last set of bores and ports to drive thepistons while the original set of bores described provide for theexhaust.

To actuate the engine valve 48 I provide a pilot valve 18 which has aflatted surface ll communicating with the port 12 opening into theintake port 42 and the annular grooves 13 and 14. A milled slot 18communicates with the exhaust port 43 by way of the bore 18. When thepilot valve 18 is moved to the right, the annular groove 13 lines upwith the bore I1 and allows the fluid, pressure to move through the bore11 and the slot I8 into the cylinder 4i at the left side of the piston39, moving the engine valve 48 to the right. At the same time the fluidin the cylinder M at the right end of the valve 48 is exhausted throughthe slot Win the casting 3 past the milled slot 18 and out through thebore 18 and the exhaust port 43. The movement of the pilot valveactuates the engine valve which in turn actuates the engine pistons.

While the pilot valve 18 can be operated by any means such as a cam,direct linkage, or by an electric solenoid control, I prefer to actuatethe same by the fluid pressures actuating my entire compressor. Toactuate the pilot valve 18 the same is provided at each end with pistons8!. The right end of the cylinder 88 is connected with a bore 82 whichcommunicates with the ports 88 and 84 in the cylinder l8. However, thepiston rod 25 is a sliding fit in the cylinder I 8 and of suflicientdiameter to seal the ports 83 and 88. There are annular grooves '85 and86 upon the piston rod 25. When the piston rod 28 is in the positionshown in Figure 3, the annular groove 88 opens a passage from the port84 into a port 81 at the end of the bore 88. This bore 88 opens into theexhaust port 43. Any fluid pressure at the right end of the cylinder 88can be discharged out through the exhaust port 43. Upon the other end ofthe piston rod 25 where it slides in the cylinder 9 are the annulargrooves 89 and 98. As shown in Figure 3, when the piston I 6 is at theleft end of its stroke, the groove 98 opens a passage between ports 9|and 92. The port 92 communicates with the bore 93 which opens into theleft end of the cylinder 88 while the port at the end of the bore 94opens into the intake port 42. When the piston I8 is at the left end ofits stroke, fluid pressure passes through into the left end of thecylinder 88 forcing the pilot valve 18 to the right and, by thepreviously described passages for the fluid pressure, moves the enginevalve 48 to the right, reversing the travel of the pistons ll, l5, i6,i1 and II. When the piston I6 is at the right end of its stroke, theannular groove 85 opens a passage from the port 95 which opens into thebores 82 and 83 to the Port 96 at the end of the bore 94, allowing thefluid pressure to flow into the right end of the cylinder 80 and forcethe pilot valve 10 to the left. The pressure in the left end of thecylinder 80 is exhausted through the bore 93 and out through the port 98past the annular groove 3! into the port 51 which is at the end of thebore 88 communicating with the exhaust port 43.

Many attempts have been made to actuate a reciprocating set of pistonsby the use of fluid passages to actuate the valving mechanism. However,all of these devices have failed in operation, because there is alwaysleakage around the ports and as the load on the engine increases thisleakage will cause the engine valve to move to a dead center positionand stop the entire operation. This is not possible in my device,because leakage cannot accumulate in the cylinder II and prevent theoperation of the engine valve as the same will always be either at theextreme left or the extreme right depending upon the position of thepilot valve 10. There is no possibility of back pressure building up onthe exhaust side of the engine valve. Only when the pilot valve 10 iscracked open to allow communication with the exhaust and the intake willthe engine valve begin to move and the slightest opening of the pilotvalve will immediately cause the engine valve to slam to the oppositeposition so that even leakage that would normally stall the engine valveis immediately exhausted.

When my compressor is running on low pressure in the supply tank, itwill cause a very violent movement of both the engine valve 40 and thepilot valve I0. At both ends of the cylinders in and 80, in the end ofthe castings 2 and I are positioned bumpers lllll formed or rubber or alike material to absorb the shock at the end of the stroke of thesevalves.

A. particular feature of my invention is the open connections betweenthe driving pistons l4, l5, l6, ll and i8 which allows the pumpingaction to gradually slow as the pressure in the reservoir tankincreases. The cross porting by the bores allows the piston to receivefull pressure and yet the violence of the pistons reciprocation isslowed by the back pressure.

While I have described the preferred embodiments of my invention, I amnot limited to any of the details therein set forth except as describedin the following claims.

I claim:

1. In a compressor, a housing, a cylinder in said housing, a powerpiston in said cylinder, 8. second cylinder in said housing, an enginevalve in said cylinder, a third cylinder in said housing, a pilot valvein said cylinder,cylinder heads carried by said housing and having portscommunlcating with said engine valve and opposite sides of said powerpiston, a pressure intake port to said engine valve, an exhaust port tosaid engine valve, means carried by said engine valve for alternatelyopening said ports to said intake port and said exhaust port toreciprocate said piston, a pilot valve, ports from said pilot valve tosaid intake port and said outlet port and ports from said pilot valve tothe opposite ends of said engine valve, means carried by said pilotvalve for alternately opening said intake port and said exhaust port toreciprocate said engine valve, cylinders in said cylinder heads,compressing pistons in said cylinders, a connecting rod connecting saidpower piston and said compressing pistons whereby movement of said powerpiston will actuate said compressing pistons, and means carried by saidconnecting rod for actuating said pilot valve.

2. In a compressor, a housing, a cylinder in said housing, a powerpiston in said cylinder, 9. second cylinder in said housing, an enginevalve in said cylinder, a third cylinder in said housing, a pilot valvein said cylinder, cylinder heads carried by said housing and havingports communicating with said engine valve and opposite sides of saidpower piston, a pressure intake port to said engine valve, an exhaustport to said engine valve, means carried by said engine valve foralternately opening said ports to said intake port and said exhaust portto reciprocate said piston. a pilot valve, ports from said pilot valveto said intake port and said outlet port and ports from said pilot valveto the opposite ends of said engine valve, means carried by said pilotvalve for alternately opening said intake port and said exhaust port toreciprocate said engine valve, cylinders in said cylinder heads,compressing pistons in said cylinders, a connecting rod connecting saidpower piston and said compressing pistons whereby movement of said powerpiston will actuate said compressing pistons, and annular grooves onsaid connecting rods, and passages from the opposite ends of said pilotvalve to a position in said cylinders in said engine housing adjacent topassages connecting with said intake port and said exhaust port, saidannular grooves spaced to alternately connect said passages uponreciprocation of said connecting rod to alternate- 1y connect the endsof said pilot valve with said intake port and said exhaust port.

ROBERT E. MI'I'ION.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 684,716 Poore et al. Oct. 15,1901 760,122 Holmberg May 17, 1904 1,081,784 Spohrer Dec. 16, 19131,224,661 Parker May 1, 1917 2,205,793 Hunt June 25, 1940 FOREIGNPATENTS Number Country Date 3,988 Great Britain Mar. 16, 1887

